#include <REGX52.H>
void Delay(int x)		//@12.000MHz
{
	while(x--)
	{
		unsigned char i, j;
	i = 2;
	j = 239;
	do
	{
		while (--j);
	} while (--i);
	}
}
void main()
{
	unsigned char num = 0;
	while(1){
		if(P3_1 == 0){
		Delay(20);
		while(P3_1 == 0);
		Delay(20);
		//1111 1111 上电后P2口默认为高电平
		num++;
		P2 = ~num;
	}
	}

}